19 July 2021

US researchers have made new discoveries which may help avoid unnecessary bone marrow biopsies in African Americans who have naturally reduced white blood cell counts.

The benign genotype, called rs2814778-CC or ‘CC’ for short, is carried by up to two-thirds of African American people, and leads to a benign reduction in the numbers of neutrophils in the blood.

Dr Sara Van Driest of Vanderbilt University Medical Center, Tennessee, USA, and colleagues looked at whether the CC genotype contributes to unnecessary bone marrow biopsies.

Information was analysed from 399 African American men and women who had a bone marrow biopsy as part of routine care between 1998 and 2020.

Of these 399, 35 people had a bone marrow biopsy solely because of a history of low white blood cell counts. When these people were tested, the ‘CC’ genotype was “highly prevalent” – present in 34 of the 35 (97%), compared to 67% of the 364 people who had a biopsy for other histories.

Among the 34 people who had a CC genotype and a biopsy solely for low white blood cell counts, the biopsy results came back as normal in 33 (97%). Among CC genotype carriers who had a biopsy for other reasons, 55% of people had a normal result.

The authors suggest that genotyping to account for rs2814778-CC may avoid unnecessary bone marrow biopsies related to isolated low white blood cell counts among African American patients.

Dr Van Driest said: “The genotype that causes lower white blood cells was almost always present in African American individuals who had a bone marrow biopsy solely for a low white blood cell count.

“We hope that in the future, we can do a better job of recognising these individuals with a benign cause for their low white blood cells counts so that bone marrow biopsies can be avoided.”

Co-author Dr Jonathan Mosley added: “Genetic variation has a large impact on the levels of biomarkers like white blood cell counts, but reference ranges are defined based on population averages without taking genotypes into account.

“We've essentially created this racial health disparity by not fully considering how genetic variation affects white blood cell levels. Our study supports genotyping African Americans before performing a bone marrow biopsy for the indication of isolated low white blood cell counts.”

The research was published in the journal JAMA Internal Medicine last week.


Van Driest SL, Abul-Husn NS, Glessner JT, Bastarache L, Nirenberg S, Schildcrout JS, Eswarappa MS, Belbin GM, Shaffer CM, Mentch F, Connolly J, Shi M, Stein CM, Roden DM, Hakonarson H, Cox NJ, Borinstein SC, Mosley JD. (2021) “Association Between a Common, Benign Genotype and Unnecessary Bone Marrow Biopsies Among African American Patients.” JAMA Internal Medicine, doi: 10.1001/jamainternmed.2021.3108

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